Đang tải... (xem toàn văn)
Microsoft Word C039217e doc Reference number ISO 16793 2005(E) © ISO 2005 INTERNATIONAL STANDARD ISO 16793 First edition 2005 02 15 Nuclear fuel technology — Guide for ceramographic preparation of UO2[.]
INTERNATIONAL STANDARD ISO 16793 First edition 2005-02-15 `,,,```-`-`,,`,,`,`,,` - Nuclear fuel technology — Guide for ceramographic preparation of UO2 sintered pellets for microstructure examination Technologie du combustible nucléaire — Guide pour la préparation céramographique de pastilles UO2 frittées pour l'examen de la microstructure Reference number ISO 16793:2005(E) Copyright International Organization for Standardization Reproduced by IHS under license with ISO No reproduction or networking permitted without license from IHS © ISO 2005 Not for Resale ISO 16793:2005(E) PDF disclaimer This PDF file may contain embedded typefaces In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing In downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy The ISO Central Secretariat accepts no liability in this area Adobe is a trademark of Adobe Systems Incorporated Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing Every care has been taken to ensure that the file is suitable for use by ISO member bodies In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below `,,,```-`-`,,`,,`,`,,` - © ISO 2005 All rights reserved Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body in the country of the requester ISO copyright office Case postale 56 • CH-1211 Geneva 20 Tel + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyright@iso.org Web www.iso.org Published in Switzerland ii Copyright International Organization for Standardization Reproduced by IHS under license with ISO No reproduction or networking permitted without license from IHS © ISO 2005 – All rights reserved Not for Resale ISO 16793:2005(E) Contents Page Foreword iv Scope Principle Procedures Essential apparatus Reagents and consumables Methods Etching `,,,```-`-`,,`,,`,`,,` - Bibliography iii © ISO 2005 – All rights reserved Copyright International Organization for Standardization Reproduced by IHS under license with ISO No reproduction or networking permitted without license from IHS Not for Resale ISO 16793:2005(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work of preparing International Standards is normally carried out through ISO technical committees Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part The main task of technical committees is to prepare International Standards Draft International Standards adopted by the technical committees are circulated to the member bodies for voting Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote ISO 16793 was prepared by Technical Committee ISO/TC 85, Nuclear energy, Subcommittee SC 5, Nuclear fuel technology iv Copyright International Organization for Standardization Reproduced by IHS under license with ISO No reproduction or networking permitted without license from IHS © ISO 2005 – All rights reserved Not for Resale `,,,```-`-`,,`,,`,`,,` - Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights ISO shall not be held responsible for identifying any or all such patent rights INTERNATIONAL STANDARD ISO 16793:2005(E) Nuclear fuel technology — Guide for ceramographic preparation of UO2 sintered pellets for microstructure examination Scope This International Standard describes the ceramographic preparation of uranium dioxide (UO2) sintered pellets for qualitative and quantitative microstructure examinations These examinations may be carried out before and after thermal or chemical etching They enable observations of fissures, inter- or intra-granular pores and inclusions, measurement of pore and grain size and measurement of pore and grain size distributions The measurement of average grain size may be carried out using a classical counting method as described in ISO 2624 or ASTM E112, i.e intercept procedure, comparison with standard grids or reference photographs The measurement of pore-size distributions is usually carried out by an automatic image analyser If the grainsize distributions are also measured with an image analyser, it is recommended that thermal etching be used to reveal the grain structure uniformly throughout the whole sample Principle Ceramographic preparation of UO2 sintered pellets is carried out in two main stages a) Sample polishing: The sample may either be mounted in resin, or held in an appropriate mechanical gripping device (an example is shown in Figure 1) b) Sample etching: The microstructure may be revealed by chemical or thermal etching Thermal etching cannot be done on a mounted sample Procedures 3.1 General Ceramographic samples can be prepared using three different procedures: the sample can be unmounted, mounted without subsequent dismounting, or mounted with subsequent dismounting `,,,```-`-`,,`,,`,`,,` - © ISO 2005 – All rights reserved Copyright International Organization for Standardization Reproduced by IHS under license with ISO No reproduction or networking permitted without license from IHS Not for Resale ISO 16793:2005(E) 3.2 Sample preparation without mounting Preparation stages: sectioning; grinding; polishing; etching (chemical or thermal) 3.3 Sample preparation with mounting, not needing subsequent dismounting Preparation stages: sectioning; mounting with any suitable resin; grinding; polishing; chemical etching 3.4 Sample preparation with mounting, needing subsequent dismounting sectioning; mounting with polyester or acrylic resin; grinding; polishing; dismounting; chemical or thermal etching Essential apparatus 4.1 `,,,```-`-`,,`,,`,`,,` - Preparation stages: Metallographic sectioning machine, with a diamond wheel and a water-inlet system 4.2 Manual polishing machine, or automatic polishing machine with a force system capable of maintaining a constant pressure on the samples, recommended between 0,8 × 105 Pa and 1,0 × 105 Pa (see Figure 2) 4.3 Ultrasonic cleaning bath 4.4 Device maintained under vacuum, with a roughing pump for impregnation 4.5 Heater, capable of heating up to 80 °C for dismounting 4.6 Thermal etching furnace, working under an oxidizing atmosphere of carbon dioxide (CO2) Both the sample and the temperature-measurement system must be in the isothermal zone of the furnace 4.7 Mechanical gripping device, for sample preparation without mounting 4.8 Optical microscope Copyright International Organization for Standardization Reproduced by IHS under license with ISO No reproduction or networking permitted without license from IHS © ISO 2005 – All rights reserved Not for Resale ISO 16793:2005(E) Reagents and consumables 5.1 Castable mounting compounds, (two or three components) with a polyester-, epoxy- or acrylic-based composition 5.2 Abrasive discs, with grits between P60 (269 µm) and P2500 (8,4 µm) 5.3 Impregnation resin, with epoxy-based composition 5.4 Alcohol, industrial grade 5.5 Diamond polishing suspensions, or pastes with diamond size between 0,25 µm and 15 µm 5.6 Nylon, silk, wool or synthetic polishing cloths, woven or non-woven 5.7 Aqueous polishing suspensions of alumina or silica, with particle sizes between 0,05 µm and µm 5.8 Hydrogen peroxide, 30 % by mass, density 1,11 kg/l 5.9 Sulfuric acid, 95 % by mass or more, density 1,84 kg/l 5.10 Hydrofluoric acid, 38 % to 40 % by mass, density 1,13 kg/l 5.11 Chromium (VI) oxide 5.12 Carbon dioxide (CO2) gas, purity W 99,995 %, or other oxidizing gas 5.13 Water 6.1 Methods Sectioning Pellet sectioning is carried out using a metallographic sectioning machine (4.1) with a diamond wheel and a water-inlet system The rotation speed of the wheel, the feed speed of the sample and the amount of water shall be selected carefully to avoid creating artefacts Pellets are usually sectioned such that the finally ground and polished surface is on the diameter of the pellet Pellets may also be sectioned transversally The sectioned sample is cleaned with water (5.13) or alcohol (5.4), with or without an ultrasonic bath (4.3) For the grinding and polishing stages, the sectioned sample is either mounted in an appropriate resin (5.1) or placed in a mechanical gripping device (4.7) to hold the sample onto the polishing machine (an example of such a device is shown in Figures and 2) 6.2 Mounting The sectioned sample may be mounted in a resin (5.1) For samples which not need to be dismounted, a liquid epoxy, polyester or acrylic resin mixed with hardener can be used according to the supplier’s instructions For samples requiring subsequent dismounting, a liquid polyester or acrylic resin mixed with hardener is used according to the supplier’s instructions These types of resin shrink more than other types during the hardening process, thus facilitating dismounting The polymerization is usually complete within 20 to 24 h at ambient temperature, depending on the type of resin used `,,,```-`-`,,`,,`,`,,` - © ISOfor2005 – All rights reserved Copyright International Organization Standardization Reproduced by IHS under license with ISO No reproduction or networking permitted without license from IHS Not for Resale ISO 16793:2005(E) 6.3 Grinding The mounted or mechanically held unmounted samples are ground on a polishing machine (4.2) The grinding is carried out in different stages as shown in the following example: abrasive paper P180 (82 µm): about to 10 of grinding is necessary for the sectioned resinmounted samples, 30 s to is sufficient for unmounted samples; abrasive paper P400 (35 µm): 30 s to min; abrasive paper P800 (22 µm): 30 s to min; abrasive paper P1200 (15 µm): 30 s to The samples are thoroughly cleaned with water (5.13) or alcohol (5.4), with or without an ultrasonic bath (4.3) after each stage 6.4 Polishing The polishing can include different stages, decreasing the roughness of the polishing cloth and the particle size of the abrasive The ground sample is polished on a short-fibre polishing cloth (5.6) with diamond abrasives (5.5) of particle sizes between 15 µm and 0,25 µm, for about 20 The polishing can be finished using aqueous suspensions of alumina or silica (5.7) with particle sizes between µm and 0,05 µm on a fine and long-fibre cloth (5.6) An automatic polishing machine (4.2) is usually used After polishing, the sample is thoroughly cleaned with alcohol (5.4) or water (5.13), with or without an ultrasonic bath (4.3) The polished surface shall be free from scratches The polishing quality is controlled by observation with a microscope (4.8), at a magnification adequate for the subsequent examinations Just before polishing, the ground surface may be impregnated under vacuum with a liquid resin in order to fill up the pores 6.5 Dismounting Polyester or acrylic resins display significant shrinkage on hardening, making rapid dismounting of the sample at low temperature possible using a simple heater For safety reasons, the temperature must be kept below the decomposition temperature of the resin according to the supplier’s data sheets (normally below 80 °C) 7.1 Etching Introduction The grain structure of the sample surface is highlighted by chemical or thermal etching © ISO 2005 – All rights reserved `,,,```-`-`,,`,,`,`,,` - Copyright International Organization for Standardization Reproduced by IHS under license with ISO No reproduction or networking permitted without license from IHS Not for Resale ISO 16793:2005(E) 7.2 Chemical etching The most common reagents of the chemical etching solutions are water, hydrogen peroxide (5.8), sulfuric acid (5.9), hydrofluoric acid (5.10) and/or chromium (VI) oxide (5.11) The proportion of each reagent and the etching time depend on the experience of the laboratory and the material As an example, the following etching solution can be used: Water (5.13) 20 ml Hydrogen peroxide (5.8) ml Sulfuric acid (5.9) ml The proportions can change slightly according to the material `,,,```-`-`,,`,,`,`,,` - The sample is etched for to min, then rinsed with water and air dried Vacuum drying may also be applied if samples must be kept clean for a longer period of time 7.3 Thermal etching Thermal etching is used for samples which are either unmounted or mounted in polyester or acrylic resin for subsequent dismounting The conditions for thermal etching are as follows: gas: CO2 or other oxidizing gas; heating rate: at least 100 °C/h; final temperature: between 300 °C and 450 °C, depending on the material; time at final temperature: 15 or more, depending on the material Key cover sliding part adjustment screw tightening screw fixed part holding and positioning apparatus for the sample Figure — Example of mechanical gripping device of a pellet © ISO 2005 – All rights reserved Copyright International Organization for Standardization Reproduced by IHS under license with ISO No reproduction or networking permitted without license from IHS Not for Resale ISO 16793:2005(E) Key gripping device sample-holding plate Figure — Positioning of the gripping device on the sample-holding place of a polishing machine `,,,```-`-`,,`,,`,`,,` - Copyright International Organization for Standardization Reproduced by IHS under license with ISO No reproduction or networking permitted without license from IHS © ISO 2005 – All rights reserved Not for Resale ISO 16793:2005(E) Bibliography ISO 2624, Copper and copper alloys — Evaluation of the average grain size [2] ASTM E112, Standard Test Methods for Determining Average Grain Size `,,,```-`-`,,`,,`,`,,` - [1] © ISO 2005 – All rights reserved Copyright International Organization for Standardization Reproduced by IHS under license with ISO No reproduction or networking permitted without license from IHS Not for Resale ISO 16793:2005(E) `,,,```-`-`,,`,,`,`,,` - ICS 27.120.30 Price based on pages © ISO 2005 – All rights reserved Copyright International Organization for Standardization Reproduced by IHS under license with ISO No reproduction or networking permitted without license from IHS Not for Resale